VLAN | 1107To configure a port so that it has a native VLAN:Change the Default VLAN IDBy default, VLAN 1 is the Default VLAN. You can make another VLAN the default (which then enablesyou to configure VLAN 1).Set the Null VLAN as the Default VLANIn a Carrier Ethernet for Metro Service environment, service providers who perform frequentreconfigurations for customers with changing requirements occasionally enable multiple interfaces, eachconnected to a different customer, before the interfaces are fully configured. This presents a vulnerabilitybecause both interfaces are initially placed in the native VLAN, VLAN 1, and for that period customers areable to access each other's networks. FTOS has a Null VLAN to eliminate this vulnerability. When youenable the Null VLAN, all ports are placed into by it default, so that even if you activate the physical portsof multiple customers, no traffic is allowed to traverse the links until each port is place in another VLAN.Step Task Command Command Mode1 Remove any Layer 2 or Layer 3 configurations from the interface. INTERFACEIf the port has any configurations on it when you enter the command portmode hybrid, FTOS rejectsthe configuration, citing the following message: % Error: Port is in Layer-2 mode .2 Configure the interface for hybrid mode. portmode hybrid INTERFACE3 Configure the interface for switchport mode. switchport INTERFACE4 Add the interface as a member of one or more VLANs. [tagged | untagged] VLAN INTERFACETask Command Syntax Command ModeMake a VLAN other than VLAN 1 the default VLAN. default vlan-id CONFIGURATIONTask Command Syntax Command ModeDisable the default VLAN, so that all ports belong tothe Null VLAN until configured as a member of anotherVLAN.default-vlan disableDefault: the default VLAN is enabled(no default-vlan disable).CONFIGURATION
